squeeze your shoulder blades together and push your chest out, ive found having my hands a close in as possible also helps tighten your back musclature. once your back develops it wont hurt as much as the muscle will act almost like padding.
Im going to be uploading a few vids of mine soon just to check form etc. It's worth doing so you can correct any bad habits now rather than months down the line.
Do or do not, there is no try.